Method of fabricating filament support loops



y 1969 R. M. BRADY ETAL METHOD OF FABRICATING FILAMENT SUPPORT LOOPS Original Filed April 20, 1964 Sheet of 2 FIG. I

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INVENTORS. ROBERT M. eeflpv, l 2

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May 6, 1969 BRADY ET AL 3,442,302

METHOD OF FABRIGATING FILAMENT SUPPORT LOOPS Original Filed April 20, 1964 heet 2 0f 2 AWE/YE Y.

INVENTORS.

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United States Patent O U.S. Cl. 14071.5 5 Claims ABSTRACT OF THE DISCLOSURE The method of forming and mounting an arcuate wire support member on an elongated filament from a spool of relatively stiff wire comprising the steps of: holding the filament in a die, inserting the free end of the support wire into the die in a direction normal to the filament, forming an enlarged body portion of several convolutions with the support wire, forming a radial spoke with the support wire from the last of the enlarged body portion convolutions to the filament and winding the support wire about the filament first in one direction and then in the reverse direction for several turns to securely lock the support Wire to the filament. The support wire is then cut adjacent the outer convolutions and upon slight expansion of the outer convolutions forming the enlarged body portion the secured end of the wire will fall well within the outer convolutions.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a division of copending application Ser. No. 361,176 filed Apr. 20, 1964, for Apparatus for Fabricating Filament Support Loops, by the present inventors and owned by the same assignee as this application said copending application having now issued as US. Patent No. 3,342,224 on Sept. 19, 1967.

BACKGROUND OF THE INVENTION The present invention relates to electric lamps utilizing an elongated metallic filament and has particular reference to the provision of supports for coaxially holding such filament interiorly of a vitreous envelope.

Incandescent iodine-filled electric lamps employing an elongated coaxially disposed metallic filament which are utilized for both heating and lighting purposes are now well known to the art. One of the most troublesome problems with lamps of this particular type has heretofore been that of properly supporting such filament coaxially of its vitreous envelope, especially since the lamp is subjected to extremely high temperature during operation thereof. In the copending application of William L. Brundige, Ser. No. 281,293, filed May 17, 1963, now Patent No. 3,270,781, and assigned to the same assignee as the present invention, a filament support, together with the method and apparatus for forming it, is shown and claimed which has proven satisfactory for its intended purposes. However, a filament support so made is subject to the disadvantage of relatively high production cost. This is due to the fact that after formation of the support by the simultaneous coiling of the inner turns and the enlarged helical body, the protruding ends of the support wire must be trimmed. This trimming operation is not only time consuming but inherently produces a certain amount of waste.

SUMMARY OF THE INVENTION It is accordingly the primary object of the present in- 3,442,302 Patented May 6, 1969 vention to produce a wire support for an elongated metallic filament, requiring a minimum of operations and leaving no waste, thereby reducing manufacturing costs.

Another object of the present invention is the provision of an improved method for fabricating a loop support for an elongated metallic filament from a continuous spool of wire wherein the enlarged helical body portion of the support is first formed followed by coiling of the inner locking turns thereof, thus necessitating but a single cut of the support wire and eliminating all waste.

The foregoing objects of the present invention together with other objects which will become apparent to those skilled in the art from the following description, are achieved by holding the free end of the support wire normal to the coiled filament by a coiling die. The enlarged helical body portion of the support is then first formed and the wire is subsequently tightly wound around the filament in the same direction to form small inner turns. The support wire is then wound tightly around the filament in a reverse direction to form several outer turns that overlie the inner turns and thus securely lock the support in its desired mounted position on the filament. Thereupon the support wire feeding from its spool is cut at a point which, upon removal of the support from the coiling die with accompanying slight expansion of the helical body portion and the changing of the inner eccentric turns to a concentric position, places the servered end of the wire well within the convolutions of the enlarged helical body portion.

BRIEF DESCRIPTION OF THE DRAWING ports of the present invention on the elongated filament;

FIG. 3 is a fragmentary rear view of the same apparatus and taken ninety degrees relative to FIG. 2;

FIG. 4 is a fragmentary view, partly in section and on an enlarged scale, of the coiling die portion of the machine of FIG. 1 and showing the support wire positioned in the die preparatory to initiation of the coiling operation;

FIG. 5 is an end view of the coiling die taken at right angles to FIG. 4;

FIG. 6 is a fragmentary view, on an enlarged scale, of the coiling die and showing completion of the formation of the enlarged helical body portion of the support;

FIG. 7 is a view of the coiling die with the enlarged helical body portion formed thereon and taken ninety degrees relative to FIG. 6;

FIG. 8 is a view similar to FIG. 6, but showing formation of the tightly-wound inner turns about the elongated filament;

FIG. 9 is an end view of the coiling die with its partially formed wire support as shown in FIG. 8;

FIG. 10 is a view similar to FIGS. 4, 6 and 8 but showing the reverse-wound overlying turns for locking the support in its desired mounted position on the filament;

FIG. 11 is an end view of the coiling die with the completely formed support thereon and in its set position 3 DESCRIPTION OF THE PREFERRED EMBODIEMNT Referring now more specifically to the drawings, a quartz-iodine lamp is shown in FIG. 1 comprising a tubular envelope 5 formed of quartz, or other high-temperature resistant transparent vitreous material, and provided with an elongated incandescible metallic filament 6 having leading-in conductors 7 and 8 connected at opposite ends thereof through suitable glass-to-metal seals 9, as is well known in the art. Such elongated filament 6 is held substantially coaxially of the tubular envelope 5 by means of spaced helical wire supports 10 formed and secured thereto in accordance with the present invention.

By reference now more particularly to FIGS. 2 and 3, an apparatus is therein shown for the forming and securing of the wire supports 10 to such elongated filament 6 at preselected spaced distances along its length. Such apparatus comprises a base 12 having an upright 13 extending therefrom with the top of the latter provided with a rearwardly projecting shaft 14 upon which a spool 15 of support wire 16 is journaled for rotation. The upright 13 also supports an elongated depending protecting tube 17 through which the wire passes to prevent inadvertent striking and breaking of the wire. Suitably journaled at 18 to the upright 13 is a drive gear 19 having a peripherally disposed turning handle 20 on its front surface and a ring-like cam 22 on its rear surface. A pinion gear 23 journaled on a bracket 24 meshes with the drive gear 19 and with a further driven gear 25 secured to a shaft 26. This shaft 26 is provided with an eccentric passageway 21 for the feeding therethrough of the elongated filament 6 while still on its forming mandrel 27, and a sleeve 28 having its inner end 29 flattened at two sides, as shown in FIG. 5, is slidable along the shaft 26 for a distance d with rotation prevented by a pin and slot arrangement 30.

An additional bracket 32 extends outwardly from the upright 13 which supports a hollow sleeve 33 housing a coil spring 34 and through which a shaft 35 longitudinally extends. The inner end of this shaft 35 is provided with a pivoted roller 36 maintained in frictional engagement with the ring-like cam 22 by the biasing action of the coil spring 34, while axial rotation of the shaft 35 is prevented by means of a pin and slot arrangement 37. A depending guide member 38 is affixed to the outer end of the shaft 35 through which the support wire 16 extends so that the lower end of such guide member 38 is movable in a horizontal plane by the action of the cam 22 forcing the shaft 35 inwardly of the hollow sleeve 33 against the biasing force of the coil spring 34 as the drive gear 19 is rotated by the operator grasping the handle 20.

By reference now to the enlarged views shown in FIGS. 4 to 11, it will be noted that the rear end of the shaft 26 comprises a forming die having a radial slot 39 and a substantially semi-annular segment 40 of maximum thickness adjacent the slot 39 which peripherally tapers to zero at a point adjacent the eccentric passageway 21 from which the coiled filament 6 on its mandrel 27 emerges. An operator first feeds the depending end of the support wire 16 into the radial slot 39, as shown in FIGS. 4 and 5, and then grasps the handle 20 thereby rotating the drive gear 19 together with the small gears 23 and 25. Such rotation accordingly rotates both the shaft 26 through which the coiled filament 6 on its mandrel wire 27 emerges, as well as the die end thereof and the sleeve 28. The depth of the die slot 39 together with the thickness of its segment 40 is such that the enlarged helical body portion 42 of the support comprising about two full turns is first formed, as seen in FIGS, 6 and 7, since the guide member 38 is moved to the right by the action of the roller 36 riding on the ring-like cam 22, until the support wire 16 rides off the thickened portion of the segment 40.

The continued rotation of the drive gear 19 thereupon causes the support wire 16 to form a spoke-like section 43 4 (FIGS. 9 and 11) after which two or three inner turns 44 (FIGS. 8 and 9) are formed in the same direction tightly about the filament 6, as the guide member 38 continues to move to the right by action of the cam 22 and roller 36 for the total distance d (FIG. 2). Upon completion of the inner turns 44 the guide member 38 is then moved to the left under urging of the coil spring 34 and the cam roller 36 to thus form two or three overlying reverse direction outer turns 45 which securely lock the support 10 in its desired mounted position on the filament 6, as shown in FIGS. 10 and 11. The operator is guided in fixing the starting and termination points for rotation of the drive gear 19 by an indicator comprising a spring-pressed ball 46 (FIG. 2) which engages a cut or start recess or indentation 47 provided in the rear hub surface of the gear 19, as seen in FIG, 3.

Consequently, upon completion of the several reverse direction outer locking turns 45, which require slightly less than one complete revolution of the drive gear 19 due to the ratio between such gear and the driven gear 25, the spring-pressed ball 46 will engage the cut indentation 47. At this time the coiling die 39-40 together with the wire support 10 formed thereon will be in the position as shown in FIG. 11, whereupon the operator sets the spoke 43 by applying force thereto, such as with a blunt instrument 48 (FIG. 11) to thus sharpen the bend of the wire 16 over the edge of the segment 40, after which the wire 16 depending from the guide member 38 is cut at the position indicated by such legend in FIG. 11. The release of tension due to this cutting results in a slight loosening of the reverse turns 45, as seen in FIG. 12, but this is so slight since such turns are set as to not affect the satisfactory locking of the inner turns 44 securely in place about the coiled filament 6.

The operator then slides the sleeve 28 longitudinally of the shaft 26 for a distance sufficient to push the formed support 10 off the end of the die 39-40 while at the same time pulling on the filament mandrel 27 until the support 10 then aflixed to the filament 6 is moved into alignment with a marker 50 (see FIG. 2) depending in a desired adjusted position from the bracket 32. Next, the operator slightly rotates the gear 19 until the springpressed ball 46 engages the start recess 47 preparatory to the operator commencing the coiling of another spaced support 10 about the coiled filament 6. Upon removal of the formed support 10 from the die end 39-40 there will be a shifting of the axis of the support 10 from its eccentric position relative to the coiled filament 6, as seen in FIG. 11, to a concentric position therewith, as shown in FIG. 12. Also, a slight expansion of the helical body portion 42 simultaneously occurs, even though its radius is held fixed by the spoke 43, resulting in the diameter of such portion 42 increasing by an amount such that the helical body portion consists of approximately one and one-quarter convolutions rather than its previous two and one-half convolutions, and both of the severed ends of the support 10 lie entirely within the confines of such convolution and substantially parallel to each other, as shown in FIG. 12.

It should accordingly be apparent to those skilled in the art from the foregoing that an improved wire support loop for an elongated metallic filament has been provided by the present invention wherein its manufacturing cost has been materially reduced since only one cut of the spooled wire is required after completion of the support. Moreover, an improved method and apparatus for making such support has been provided wherein the support is formed as a continuous winding in which the enlarged helical body portion is first formed sequentially followed by the formation of the small inner turns and the overlying reverse direction outer turns. Thereafter, the formed support firmly secured to the coiled filament is severed from the spooled wire by a single cut and then removed from the coiling die whereupon the r resultant expansion of such support places the cut end of the wire well within the convolutions of the enlarged helical body portion of the finished support.

Although one embodiment of the present invention has been herein shown and described, it is to be understood that still further modifications thereof may be made without departing from the spirit and scope thereof.

What is claimed is:

1. The method of forming and mounting an arcuate wire support member on an elongated filament from a spool of relatively stiff wire, which method comprises, holding the filament in a die, inserting the free end of the wire from said spool into a slot in said die, wrapping the wire about the outer periphery of said die at the end thereof to form an enlarged body portion of several convolutions, forming a radial spoke section that extends across the face of said die from the last convolution of the enlarged body portion to the elongated filament, winding said wire in the same direction tightly about said filament to form an inner winding of several turns, reversing the direction of winding to produce an overlying outer winding on said inner winding and hold it securely upon said filament, cutting said wire adjacent the convolution of said enlarged body portion, and removing the formed support and attached filament from said die.

2. The method of forming and mounting an arcuate wire support member on an elongated filament from a spool of relatively stiff wire, which method comprises, holding the filament in a die, positioning the free end of the wire from said spool in a radial slot in said die that extends in a direction normal to the elongated filament, wrapping the wire about the outer periphery of said die at the end thereof to form an enlarged helical body portion of several convolutions, forming a radial spoke section that extends across the face of said die from the last convolution of the enlarged helical body portion to the elongated filament, winding said wire in the same direction tightly about said filament to form an inner winding of several turns, reversing the direction of winding to produce an overlying outer Winding on said inner winding and hold it securely upon said filament, cutting said wire closely adjacent the convolution of said enlarged helical body portion, and removing the formed support from said die so that the resultant expansion of the enlarged body portion shifts said filament from an eccentric position to a concentric position relative to said support and the cut end of said support is disposed entirely within the area bounded by the convolution of said enlarged portion.

3. The method of forming and mounting an arcuate wire support member on an elongated filament from a spool of relatively stiff wire, comprising the steps of: inserting the free end of said wire into a slot in a forming die carrying said elongated filament, forming an enlarged helical body portion with said wire about the outer periphery of said forming die, extending said wire radially inwardly to said filament from said helical body portion and winding said wire snugly therea'bout in a first direction to form a first winding on said filament, reversing the direction of winding to form a second winding in a second direction overlying said first winding, and cutting said wire adjacent said helical body portion whereby upon slight expansion of said helical body portion the cut end of said wire will be within the convolutions of said helical body portion.

'4. The method of forming and mounting an arcuate wire support member on an elongated filament from a spool of relatively stifi wire according to claim 3 wherein said free end of said wire is inserted into the slot in the forming die in a direction normal to the elongated filament.

5. The method of forming and mounting an arcuate wire support member on an elongated filament from a spool of relatively stiff wire according to claim 4 wherein said first winding on said filament is wound in the same direction as said helical body portion.

References Cited UNITED STATES PATENTS 3,168,670 2/ 1965 Levand 313-274 3,194,999 7/1965 Heinlein 3 13-271 3,270,781 9/ 1966 Brundige -715 CHARLES W. LANHAM, Primary Examiner.

L. A. LARSON, Assistant Examiner.

US. Cl. X.R. 

